1. Field of the Invention
This invention relates to a process for preparing a planographic printing plate using silver halide photosensitive materials which are tanning-developable. More particularly, this invention relates to a process for preparing a planographic printing plate using photosensitive materials forming a tough relief image.
2. Description of the Prior Art
Hitherto silver halide photosensitive materials which can be tanning developed to form relief images are known, e.g., as disclosed in F. J. Drago et al Image Technology, Vol. 15, No. 1 page 20 (1973). However, all of the images formed by these photosensitive materials are physically weak and, furthermore, have low resistance to other chemicals. It is known to form a relief image on a support having a hydrophilic surface in a similar manner and to use the thus obtained silver halide photosensitive material as a printing plate, e.g., as disclosed in U.S. Pat. Nos. 2,751,295, 3,402,045, 3,364,024 and 3,669,018 and U.S. Defensive Publications T. 875,030 and T. 825,262. However, this relief image has a low degree of ink receptivity and also has low abrasion resistance and, therefore, this printing plate is used only in the field of office copying. An object of this invention is to overcome these defects of prior art materials.